Hydraulic unit for variable pitch propellers



Dec. 10, 1935- w 3 HOOVER 2,023,785

HYDRAULIC UNIT FOR VARIABLE PITCH PROPELLERS Filed June 7, 1953 I 3Sheets-Sheet 1 INVENTOR BY MA. I

ATTORNEY Dec. 10,1935.

HYDFAULIC UNIT w. s. HOOVER Filed June '7, 1933 5 Sheets-Sheet 2 Dec.10, 1935. w. s. HOOVER 2,023,785

HYDRAULIC UNIT FOR VARIABLE PITCH PROPELLERS Filed June 7, 1935 3Sheets-Sheet 5 INVENTOR M 5. A ma.-

Patented Dec. 10, 1935 PATENT OFFICE HYDRAULIC UNIT FOR VARIABLE PITCHPBOPELLEBS Walter s. Hoover, Meadvilie, Pa. Application June 7, 1933,Serial No. 674,883

9 Claims.

This invention relates to variable pitch propeller mechanism, and thepresent application is a continuation in part of an application bearingSerial No. 578,513, flledDecember 21, 1931, allowed February 27, 1934.

In the application referred to, I have disclosed a hydraulic unit in theform of an angularly movable abutment or piston element which isactuated by the fluid pressure of the oil in the engine to effectangular movement of the propeller blade hub to vary the pitch setting.The hydraulic unit therein disclosed is responsive to variations in theengine speeds to effect propeller blade pitch settings in accordancewith the speed and load characteristics of the engine.

In accordance with the present invention, I uti lize the rotary abutmentor piston elementof the hydraulic unit disclosed in my formerapplication and employ a manual control for varying the fluid pressureacting upon the hydraulic unit in accordance with the pitch setting itis desired to produce.

The invention will become more apparent from a consideration of theaccompanying drawings 7 constituting a part hereof in which likereference characters. designate like parts and in which:

Figure 1 is a side elevational view partially in section of a variablepitch propeller mechanism embodying the principles of this invention;

Figure 2 a sectional elevational view taken along the lines 2-2 ofFigure 1;

Figure 3 a cross-sectional view taken along the lines 3 3 of Figure 1;

Figure 4 a top plan view showing the propeller blade root incross-section; and,

Figure 5 a front elevational view of the propeller hub.

With reference to Figure 1 of the drawings, the structure thereinillustrated comprises an integrally forged propeller huh I with lugs 2on the rear portion thereof, and having oppositely disposed threaded hubportions 3 for receiving bearing sleeves 4 which are provided withshoulders 5 that abut against the ends of the hub element.

The bearing sleeves 4 are assembled with their threaded portionsco-acting with the threads 3 of the hub and when screwed down with theirshoulders 5 abut the ends of the hub portion. The sleeves l are providedwith an inwardly depending radial flange 1 for holding a series ofroller bearings 8 which constitute an anti-friction mounting for theroot portions 9 of the propeller blades. The blade roots 9 are furtherprovided with anchorage grooves or abutments ll that interact withcomplementary shaped abutments of split rings II that constitute ashoulder or end abutment for the anti-friction bearings I.

Disposed around the split rings H are bevelled gear wheels l2 havingteeth It that interact with a the teeth of a mating gear wheel ii. Thebevel gear II is provided with gear teeth I! constituting it an internalring gear which teeth interact with the teeth of planetary gear wheelsit that are Journalled on stud shafts l'l retained in one 10 wall l8 ofa hydraulic unit of which the casing l3 constitutes the front part orhousing.

The gear wheels l6 also mesh or interact with the teeth of a sun gearwhich is keyed at 2! to a shaft 22 extending through the walls l3 l5 andIQ of the hydraulic unit, and the design shown in the drawings is suchas to effect a five to one gear reduction between shaft 22 and the gearwheel l2.

with reference to Figure 3 of the drawings, :0 which is a cross-sectionthrough the hydraulic unit, a pair of stationary abutments 23 cooperatewith a pair of movable abutments 24 that are joined to the shaft 22 toadapt them to rotate therewith, .the movable abutments being provided 25with flow passages 25 in which are disposed safety ball valves 26 thatare normally biased against their seats by springs 21. The stationaryabutments 23 are provided with drilled leads 28 connecting fluidpassages 29, and the shaft 22 is 30 provided with passages 30 toestablish communication between the stationary and movableabutments 23and 24 on opposite sides thereof.

Again referring to Figure 1 of the drawings, the reference numeral 3|designates the engine as shaft which is hollow and has a tube 32disposed centrally and axially thereof. The inner end of tube 32 isdisposed in a counterbore provided in a sleeve or distributor headhaving fluid passages 34, 35 and 3 6, the end of the sleeve being closedby a screw plug 31 as shown.

One end of the head 33 is-provided with a screw thread 38 whichinteracts with a thread formed on the-end of a tube 33 that extends partway' into the hollow interior of the engine shaft 3|. The engine shaft3| functions as a conduit that communicates with the crank shaft of theengine for the flow of oil in the direction of the hydraulic unit, theoil passing through the space 40 between the central tube 32, and themember 33 into the hollow of the distributor head or sleeve 33, and fromwhich it is distributed in a manner to be explained in connection withFigures 4 and 5 of the drawings.

Disposed around the rear portion of the pro- 5 peller hub casting is asleeve 4| having a dishshaped flange or plate 42 provided withperforations 43 for fastening the same to the nose of the motor, and theflange or plate 42 is stationary when the propeller hub structure isrotated by the propeller shaft 8|.

Mounted on the stationary sleeve 4| are a pair of control cams 44 and 45which cooperate with plungers 46 and 41 that are disposed in cylinders48 and 48a of the lugs 2 of the hub casting. The ends of cylinders 48and 48a are closed by caps 49, and fluid passages 50 lead from thecylinders to the fluid passages of the distributor head 33 in the centerof the hub structure and to the hydraulic unit, as will be hereinafterdescribed.

The stationary cams 44 and 45 are angularly movable on sleeve 4| bylevers 5| and 52, these levers being manually operable to constitute thecontrol for varying the pitch setting, lever 5| being for forward pitchcontrol setting and lever 52 for reverse pitch control setting.

The flow connections of the cylinders 48 with the hydraulic unit and theoil supply are shown in Figures 3 to 5 of the drawings and are asfollows: The passage 36 of the oil distributing head 33 whichcommunicates with the passage 40 leading to the source of oil supply inthe crank case is shown connected at one end by drilled passages 53 and54 to one of the plunger cylinders 48 which acts as a booster to deliverthe oil under pressure through the passages 55 and 56 to the passage 23of the hydraulic unit into which it passes through passage 28 of thestationary abutment. A ball valve 51 is normally held by a spring 58 inposition to close the passage 56 and open the drain passage 35' to tube32. When the pressure in lines 55 and 56 exceeds the pressure in thepassage 34, the ball valve 51 will be displaced to close the passage 34and permit the fluid under pressure to be conducted downwardly throughpassage 29 to the passages 28 of the stationary abutments.

As there are two stationary abutments and two passages for communicatingfluid pressure into the hydraulic unit, they each have a flow system asdescribed in connection with Figure 4 of the drawings to get a reversalof the pitch setting.

With reference to Figure 3 of the drawings, when the fluid underpressure enters the passage 29 and thence through the drilled passage 28into the space between the stationary and movable abutments on one side,the fluid pressure will pass through the communicating passage 38 intothe opposite space to exert pressure against the movable abutments,causing rotation of the movable members in a given direction. Whilepressure is so exerted on one face of each of the movable abutments, thepressure on the opposite sides of. the movable abutments is relievedthrough the passages 28 and 29 that are in communication with the returnconduit 32 through passage 35 to return the fluid to the engine crankcase or pump.

When the fluid pressure is equalized on both sides of therotary'abutments 24, the blades are locked against movement for pitchsetting, and if for any reason the fluid pressure is not released on theside against which the booster pressure of the pistons 46 and 41 isacting, the safety ball members 26 will depress the spring 21 and permita balance of the fluid on both sides of the rotary abutments.

As shown in Figure 2 there are two pumping units comprising cylinders 48and 48a and pistons 46 and 41 each cylinder of which is connected to theflow passage 28 of one of the stationary abutments of the hydraulicunit. By moving control levers 5| and 52 the cams 44 and 46 to whichthey are connected will control movement of their respective pistons 46and 41. In Figure 2 of the drawings the lever 5| controlling the forwardpitch setting is shown in the position where its cam is out of 'contactwith piston 46 and the fluid in the passages connecting cylinder 48 isof the pressure of the fluid delivered through passage 40 from theengine which is from seventy flve to ninety pounds. Lever 52 is shown inthe position where cam 45 produces stroke of booster plunger 41 and thefluid passages connecting the hydraulic unit with this cylinder deliversfluid at a pressure up to flve hundred pounds per square inch dependingupon the setting of the reverse pitch control lever 52.

The employment of the flve to one gear reduction between shaft 22 of thehydraulic unit and bevel gear I2 and the flve hundred pounds per inchpressure produces approximately fifty thousand inch pounds mechanicalleverage in the adjustment control of the blade pitch. The mechanicalleverage may be increased by employing double acting hydraulic pistonsto obtain a surplus mechanical leverage.

Again referring to Figures 3 to 5 of the drawings, when one of thecontrol levers has been set to cause a boosting of the oil pressure forforward or reverse pitch setting, movement of the rotary abutments 24 iseffected by the pressure being relieved on the opposite side of theabutment through passages 28 and 29 thence by displacement of ball valve51 through passage 35 to line 32. Figure 4 shows the flow passages forone of the booster cylinders, hydraulic unit abutment and return throughline 32 as controlled by one of the control levers, and Figure 5 showthat the passages are the same for the flow as controlled by the otherof said levers.

The desired pitch setting when once obtained is maintained by thelocking effect of the oil pressures on both sides of the rotaryabutments 24 which can be produced by adjustment of both levers 5| and52. In the position of the levers in Figure 2 of the drawings, thehydraulic unit would be in its extreme reverse pitch setting, while inFigure 3 it is shown in neutral or normal pitch setting position.

It is evident from the foregoing description of U my device that theemployment of the oil pressure booster renders the hydraulic unitapplicable for use in planes where manual pitch set ting of thepropeller blades is desirable.

I Various modifications in the details of construction and arrangementof parts may be contemplated within the spirit of my invention.

I claim:

1. In a variable pitch propeller mechanism, a

hub structure for mounting a plurality of propeller blades for rotarymovement about their longitudinal axis, gear mechanism connecting saidblades to render them movable simultaneously, an hydraulic unit foractuating said gear mechanism, a source of fluid pressure for said unit,means for selectively applying pressure to said unit to render sameoperative in opposite directions, pump mechanism operative in responseto rotary movement of said propeller mechanism for varying the pressuresto produce a desired forward or reverse pitch setting of the propellerblades and ,manual control means for regulating said pump mechanism.

2. In a variable pitch propeller mechanism, a

hub structure for mounting a plurality oi! propeller blades for rotarymovement about their longitudinal'axes, an hydraulic unit embodying aplurality of stationary and movable abutments connected to subject saidblades to movement simultaneously to vary their pitch setting, fluidpressure means for displacing said abutments, fluid pressure cylindersconnected to said fluid pressure means, pistons in said cylinders, aplurality of cams cooperating with said pistons and manual control meansfor varying the cam setting to vary the length of stroke of said pistonsthereby varying the fluid pressure delivered to said hydraulicunit'abutments.

3. In a variable pitch propeller mechanism, a hub structure for mountinga plurality of propeller blades for rotary movement about theirlongitudinal axes, gear mechanism connecting said blades to render themmovable simultaneously, a hydraulicunit actuating said gear mechanism,embodying a plurality of movable piston elements, fluid pressure meansfor actuating said pistons, a plurality of fluid pressure cylindersconnected to said fluid pressure means, pistons for said last namedcylinders, a plurality of stationary cams cooperating with said lastnamed pistons, and manual control means for varying the setting of-saidcams to. thereby vary the stroke of said pistons to change the directionof movementand the pressure acting on said first named piston elements.

4. In a variable pitch propeller machanism, a hub structure for mountinga plurality of propeller blades for rotary movement about theirlongitudinal axes, differential gearing connecting said blades to renderthem movable simultaneously, a hydraulic unit for actuating said gearingembodying a plurality of displaceable piston elements, fluid pressurecylinders carried by said hub structure having piston elements disposedtherein, a plurality of stationary cams and control means therefor, saidcams being in cooperative engagement with the pistons 01' said fluidpressure cylinders, one of said controls being operative to direct theflow and vary the intensity of fluid pressure on the hydraulic unit topro-' duce a forward pitch setting of the propeller blade and the otherof said controls being efiective to control the direction and intensityof fluid pressure to said unit to eflect a reverse pitch setting of saidblades.

Y 5. In a variable pitch propeller mechanism, a

hub structure for mounting a plurality of propeller blades for rotarymovement about their longitudinal axes, a hydraulic unitconnecting saidblades to render them simultaneously movable, a plurality of movable andstationary abutments in said hydraulic unit, fluid pressure means foreflecting displacement of said abutments comprising a plurality of fluidpressure cylinders connected to a. source 01' oil supply and oil returnpassage in the engine shaft, and having pistons for boosting thepressure in said passages, flow passages leading from said cylinder tothe hydraulic unit and manual control means for controlling the pressurein said passages.

6. In a variable pitch propeller mechanism, a hub structure for mountinga plurality of propeller blades for rotary movement about their 5longitudinal axes, gear wheels mounted on said blades, a gear wheelinteracting with'the teeth of the wheels on said blades to render themsimultaneously operative, an hydraulic unit embodying a plurality ofstationary and. movable vabutments, the latter being joinedtotheintermeshing gear wheel to actuate the blades to vary their pitchsetting, a source of fluid pressure for said unit, pump mechanismoperative in response to rotary movement of said propeller mechanism forvarying the pressure of the fluid for said unit, means for selectivelyapplying fluid pressure to said unit to render it operative in oppositedirections, and means independent of said last named means forregulating the fluid pressure of said pump mechanism.

'7. In a variable pitch propeller mechanism, a hub structure formounting a plurality of propeller blades for rotary movement about theirlongitudinal axes, operating mechanism for 51- multaneously subjectingsaid blades to angular allel blades for angular movement about theirlongitudinal axes, hydraulicdisplacement means for simultaneouslysubjecting the blades to variable pitch setting, said hydraulicdisplacement means being connected to employ the lubricating 40 fluid ofthe drivemotonpump mechanism for circulating the lubricating fluid andfor boostingthe pressure of said fluid in its application tosaidhydraulic displacement means, and control means for regulating thefluid pressure delivered by said pump .9. In a variable pitch propellermechanism, a hub structure for mounting a plurality of propeller bladesfor rotary movement about their longitudinal axes, hydraulicdisplacement means 60 I for simultaneously subjecting the blades tovariable pitch setting, a source of fluid pressure for saiddisplacementmeans, means for selectively applying fluid pressure to saiddisplacement means to render same operative in opposite directions, pumpmechanism for circulating the pressure fluid and for boosting thepressure or the fluid in its application to said hydraulic displacementmeans, said pump mechanism being operative in response to rotarymovement of said pro- 6 peller mechanism, and control means forregulating the fluid pressure delivered by said pump.

WALTER. s. noovna.

